Field of the Invention
Embodiments of the present invention relate to a method for testing whether or not a display panel is normally operated.
Discussion of the Related Art
Display devices such as a liquid crystal display (LCD), organic light-emitting diodes (OLED), plasma display panel (PDP) and electrophoretic display (EPD) may be manufactured by various processes including a process of testing lighting for a display panel. In more detail, an image is displayed on the display panel included in the display device. The process of testing lighting can be performed by supplying a predetermined test signal to the display panel, and testing whether or not the display panel is normally operated according to the predetermined test signal.
For example, FIG. 1 is a schematic view illustrating a related art display panel, and FIG. 2 is a schematic view illustrating the display panel when a process of testing lighting is performed.
Referring to FIG. 1, the related art display panel 10 includes a display part 11 and a testing part 12. The display part 11 includes a plurality of sub-pixels SP defined by a plurality of gate lines GL1 to GLn and a plurality of data lines DL1 to DLm, in which the gate line and the data line cross each other. The plurality of data lines DL1 to DLm are also connected to the testing part 12.
Further, the testing part 12 alternately supplies a positive polarity (+) test signal and a negative polarity (−) test signal with respect to a common voltage Vcom to the data lines DL1 to DLm. That is, the testing part 12 transmit the positive polarity (+) test signal and the negative polarity (−) test signal, which are supplied from a testing apparatus, to the data lines DL1 to DLm, whereby the positive polarity (+) test signal and the negative polarity (−) test signal are alternately supplied to the data lines DL1 to DLm. The data lines DL1 to DLm are also connected to the testing part 12 through one connection line.
As the testing part 12 alternately supplies the positive polarity (+) test signal and the negative polarity (−) test signal to the data lines DL1 to DLm, the sub-pixels SP included in the display panel 10 according to the related art are driven and emit light in units of a frame, to thereby perform a lighting test. For example, all the sub-pixels SP of the display panel 10 according to the related art are driven according to the positive polarity (+) test signal during a first frame, and then all the sub-pixels SP are driven according to the negative polarity (−) test signal during a second frame.
According to these repetitive driving operations, the lighting test is performed. That is, a frame inversion method is performed by repetitively inverting a voltage polarity in unit of a frame in all the sub-pixels SP of the display panel 10 according to the related art.
However, because the lighting test is performed in the frame inversion method, a flicker occurs due to a low frequency for the test signal, which causes problems in the lighting test. In order to overcome this flicker problem, a method of increasing a frequency for the test signal has been proposed. However, if the frequency is increased for the test signal, the time for applying the positive polarity (+) test signal and negative polarity (−) test signal to the data lines DL1 to DLm becomes short. Thus, as shown in FIG. 2, some of the sub-pixels SP included in the display panel 10 are driven in an incomplete charging state, whereby a lighting level in some sub-pixels SP driven in the incomplete charging state is relatively lower. Therefore, based on the testing results, even though the sub-pixels SP have a good quality, a classification the lighting level in the sub-pixels SP is marked as having a poor quality.